On Tue, Feb 9, 2010 at 09:53, David Kerr <dmk@xxxxxxxxxxxxxx> wrote: > Guillaume Lelarge wrote: >> >> Le 09/02/2010 09:35, David Kerr a écrit : >>> >>> Guillaume Lelarge wrote: >>>> >>>> Le 09/02/2010 05:49, John R Pierce a écrit : >>>>> >>>>> David Kerr wrote: >>>>>>>> >>>>>>>> maintenance_work_mem = 1GB >>>>>>> >>>>>>> So evidently, when it tries to actually allocate 1GB, it can't do it. >>>>>>> Ergo, that setting is too high for your machine. >>>>>>> ... >>>>>> >>>>>> seems like i've got 2GB free. >>>>> >>>>> is this a 64bit postgres build? >>>>> >>>>> if not, you're probably running out of virtual address space in the 32 >>>>> bit user space, which is limited to like 2gb. >>>>> >>>> IIRC, the virtual address space in 32bit platforms is 4GB. IIRC, on Linux that will be a max of 3Gb available to userspace processes. Certainly not 4Gb - but it could be 2. >>> it is a 32bit box. >>> >>>>> the other possibility, and here I'm not sure, is that >>>>> maintenance_work_mem is coming out of shared memory, and if so, you've >>>>> exceeeded your SHMMAX kernel limit. >>>>> >>>> work_mem and maintenance_work_mem are not shared memory. AFAICT, David >>>> need to check if the VACUUM works with a lower setting for >>>> maintenance_work_mem. For example, 512MB could work. >>>> >>>> >>> Yes, vacuum -z works with 512MB. so any idea what was causing it not to >>> work with 1GB? >>> >> >> Tom already explained that. The process couldn't get the 1GB it was >> allowed to use with this setting of maintenance_work_mem. >> >> > Well, that made sense until I freed up a lot of memory on the box. I had > tried it again with 2GB of free memory available to me to use. My ulimits > are all unlimited. So i'm wondering if there's a kernel setting I need, or > something similar. You may well be running out of *address space* rather than pure memory. PostgreSQL is failing to allocate 1Gb of *continuous* memory. Not just 1Gb of memory anywhere. Shared memory, for example, lives at a fixed location already. There may be >1Gb free in the address space, just not where you need it. In general, when you are starting to talk about things like 1Gb maintenance_work_mem, you should've switched to 64-bit a while ago :-) > oh, hmm, my swap is 517Megs, that probably isn't helping. Usually swap is > 1.5/2x available memory, isn't it? (it is for most unix's and oracle, but > i'm not sure about PG and linux) I don't think that affects this problem. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
